1. Field of the Invention
The present invention relates to a method of evaluating a silicon wafer, and more particularly, to a method of evaluating a silicon wafer permitting evaluation of the absence or presence, and surface distribution, of oxygen precipitates in a silicon wafer utilizing photoluminescence.
The present invention further relates to a method of manufacturing a silicon wafer capable of providing a high-quality silicon wafer the quality of which is assured by the above evaluation method.
2. Discussion of the Background
When a silicon wafer containing oxygen precipitates is employed as a substrate of a semiconductor device and the oxygen precipitates are present in the active region of the device, they compromise device characteristics by lowering the dielectric strength voltage of gate oxide films, increasing the junction leak current, and the like. Additionally, when they are present in the bulk outside the active region of the device, they effectively serve as a gettering source, trapping heavy metal contamination that has mixed in during device processing. Accordingly, to fabricate high-quality devices, it is important to determine the absence or presence, and surface distribution, of oxygen precipitates in silicon wafers.
Infrared interference methods and infrared scattering methods have conventionally been employed as methods of evaluating oxygen precipitates in silicon wafers (for example, see Japanese Unexamined Patent Publication (KOKAI) No. 2002-246429, which is expressly incorporated herein by reference in its entirety).
In a silicon wafer of relatively high substrate resistivity, the substrate will have high infrared transmittance. Thus, it is possible to evaluate oxygen precipitates with high precision by methods utilizing infrared radiation. However, in low resistance p+ substrates and p/p+ silicon wafers (having a p-type epitaxial layer over a p+ substrate), the infrared transmittance of the substrate is low. Thus, in methods employing infrared radiation, evaluation of the absence or presence of interior defects in the form of oxygen precipitates, and their surface distribution, is difficult.